Retrograde brake for stretcher elevating mechanism



RETROGRADE BRK FOR STRETCHER ELEVATING MECHANISM Filez@ Jua@ 2345,? l 2 Shams-Sheet 1 L. QU@

RETROGRADE BRKE FOR STRETCHER ELEVATING MECHANISM '2 Suegras-sheet 2 Piland Jun@ 2%, 19555 K m@ mf WM M a 3,217 348 RETROGRADE )BRAKE FR STRETCHER ELEVATHNG MECHANUSM Ronald L. Duri', Granada Hills, Salif., assigner to Everest 8: Jennings, llnc.,"1los Angeles, Calif., n corporation of California v Filed .lune 24, 1963, Ser. No. 289,975

S Claims.. (El. -63) for raising and lowering the stretcher frame relative to the Wheeled main frame, and they have also included means for locking the stretcher frame in a desired elevated position against retrograde or downward movement under the weight of the stretcher frame and/or the weight of a patient resting thereon.

One of the objects of the invention is to provide irnproved means for `locking the stretcher frame against retrograde or downward movement, which means is silent in operating and therefore does not disrupt the desired quiet vin a hospital environment.

Another object of the invention .is to provide a device of the class described wherein a friction brake is interposed between an overrunning clutch and the stretcher frame elevator, the overrunning clutch locking the elevator against retrograde or downward movement, and the friction lbrake having its braking surfaces held in engagevment by at least a portion of the weight moment of the stretcher frame, and means for moving one part of the friction brake relative to the other while they are still in braking engagement when the elevator is actuated to lower the stretcher frame. v

The above and other objects will more fully appear from the following description in connection with the accompanying drawings, in which:

FIG. l is a side elevational view of a wheeled stretcher embodying the invention with the stretcher frame elevator shown in full and broken lines in raised and lowered positions respectively;

FIG. 2 is an enlarged sectional View taken approximately on the line 22 of FIG. l;

FIG. 3 is a sectional view on a larger scale taken approximately on the line 3-3 of FIG. 2;

FIG. 4 is an enlarged sectional detail taken approximately on the line 4-4 of FIG. 3;

FIG. 5 is an enlarged detail taken approximately on the line S-5 of FIG. 3; and

FIG. 6 is an enlarged detail taken approximately on the line 6-6 of FIG. 4.

In FIG. 1 there is shown a main frame 8 having lower longitudinal members 18 and upper longitudinal members l2, the latter having downwardly turned portions 14 comprising vertical end members to which the lower horizontal members 10 are connected. The lower ends of the vertical end members 1d are provided with suitable caster wheels 16. Extending between the vertical end members 14 at the left end of the main frame 8 is a horizontal cross member 18, and a longitudinal horizontal bracing member extends from the center of the cross member 18 to the center of an inverted U-shaped cross member 22.

A stretcher frame, indicated generally at 24, is disposed above the main frame 8 and is of conventional construction having a horizontal portion 26 supporting a mattress 28 and preferably having a pair of side rails 38 and a head rail 32. Secured to and extending downwardly from each of the stretcher frame horizontal portions 26 at each side and adjacent each end of the frame are plates ainsi@ Patentedv Nov. 16, 1965 34 between opposite pairs of which extend tubular cross members 36, these cross members also extending through outwardly disposed straps 38 which support the side rails or fencesl 30. Supporting the entire stretcher frame 28 are stretcher frame elevators, indicated generally at 40, in the form of lazy tongs lever units. Each set of lazy tongs 40 at opposite end portions of the stretcher frame 24 are connected to and supported by elevator actuating mechanism, to be described.

Supporting means -for the lazy tongs or stretcher elevator 48 at the left end of the structure comprises the cross member 18, the inverted U-shaped cross member 22, and the horizontal member 20 which connects them. The elevator 48 at the right end of the apparatus is sup ported by a pair of inverted U-shaped cross members 42 and all and a horizontal member 46'connecting said cross members.

inasmuch as the elevator actuating mechanism at each end of the apparatus is the same only one will be de- 'scribed in detail, the one more specifically illustrated being shown in FIGS. 2 through 6, which is the actuating mechanism at the left end of the apparatus.

The lazy tongs 48 at the lower end of the unit includes' opposed' pairs of levers 48 and 50. The pair of levers 5t), shown n FIG. 2, are pivotally connected to lugs 52 extending upwardly from the inverted U-shaped cross member 22 and between which extend a tube 54. At the center of the tube 54 is a bearing block 56 within which is a roller bearing unit 58, shown in FIG. 3, which rotatably supports the right unthreaded end 60 of a screw shaft 62 having a ball screw thread 64. v

The oppositel'y disposed lower lazy tongs vlevers 48 are pivotally connected to a cross tube 66 whose medial v supported by a pair of lugs 82 extending upwardly from the tubular cross member 18. To the right of the bearing housing 80, as viewed in FIG. 3, is a thrust bearing 84 which has in contact therewith one side of a clutch dics 86, said disc being rotatable relative to the right portion 88 of the shaft 60, 62. The shaft portion 88 i to the right of the clutch disc 86 is provided with an.

integral ilange 90 and a flat ring of friction brake ma terial 92,is secured to one face thereof between saidy ilange and the right face of the clutch disc 86.

Mounted upon the tubular cross member 18 is a block 94 having an offset portion 96 which is provided with a pair of tapered vertical channels 98 which have their adjacent portion open to each other and which reduce in taper in a downward direct-ion. The channels 98 are generally circular in cross section and each contains a ball 108. Thus, when the clutch disc 86 is interposed between the balls 100 in a slot 182 in the offset portion- 96 of block 94, said disc can be rotated freely in a clockwise direction, when viewed on the line 5-5 of FIG. 3,

but will be locked against counterclocltwise rotationi by the balls 108 which will wedge in the channels 98 and against the clutch disc. In the event the channels 98 are not disposed vertically, springs 104i are provided to yieldably urge the balls to the more restricted portions of their respective channels 98. A suitable closure 186 closes the larger ends of the channels 98 and may 'I be secured to the block portion 96 by means of a suitable agusto a slight difference in the tubular supports therefor, which were described above as 42, 44 and 46. In this right hand construction, the overrunning clutch block 96 is supported between a pair of lugs lll@ which extend upwardly from the inverted U-shaped cross member 42, and the roller bearing housing 56 is supported between a pair of lugs )112 extending upwardly from the inverted U-shaped cross member 44.

Extending through the right screw shaft 62 is a crank shaft 114 which has a hand crank M6 suitably connected to its right end. The crank shaft U4 is splined in the right screw shaft 62, and the left end of said crank shaft is splined in the Unthreaded end 6@ of the left screw shaft 62. Rotation of the crank ille' rotates the crank shaft 114 and the screw shaft 62, the latter serving as ,actuator screws for the elevators40.

In operation, when the crank 116 is rotated in a clockwise direction, as determined when facing the crank from the right end of the apparatus, the crank shaft lid will be rotated causing the bell cages or screw followers 68 to move along the ball .threads 64 from left to right. This will similarly movethe lower end of the pairs of lazy tongs levers 48 toward their cooperating lazy tongs levers 501, whose lower ends are pivotally anchored on the roller bearing housings '56. This will cause an extension of the lazy tongs in an upward direction and raise the stretcher frame 24.

During this clockwise rotation of the. crank lille and screw shafts 62, the clutch discs 86 will rotate likewise due to the frictional contact of the friction brake ring 92 with the right face of eachclutch disc. lt will be seen from FIGS. 4, 5 and 6, that in this clockwise rotation, the overruning clutch balls lil@ permit the disc 66 to rotate freely. When the stretcher frame 24 has been raised to the desired extent, the overrunning clutch balls itl@ will tightly grip the clutch disc 36 immediately upon stopping of the movement of the crank M6, and prevent reverse movement of the screw followers 68v on their respective screw shafts 62 under the weight of the stretcher frame and its occupant. This engagement of the overrunning clutch balls tot) with the clutch disc S6 takes place quietly and without shock, and during the entire raising movement, the clutch disc 36 rotates without noise by reason of the smooth contact of the `clutch balls 10o with said disc.

When lowering of the stretcher frame 24 is desired, the crank M6 is rotated in a counterclockwise direction, and of course the screw shafts 62 will rotate in like manner. The clutch disc 86 cannot similarly rotate because it is held by the overrunning clutch'balls ltltl, but the coefficient of friction between the friction brake ring 92 and the right face of the clutch disc 36 is such that, while it is sufficient to maintain the stretcher' frame in an elevated position, the screw shafts 62, and the friction brake ring 92, can rotate relative to the clutch disc 86. The material of the friction brake ring 92, and its area of contact with the clutch disc 86;, determined the degree of friction required to keep the stretcher frame in an elevated position with a patient thereon, and yet permit slippage between the friction ring 92 and clutch disc 86 when counterclockwise rotational force `is exerted by hand on the crank 116.

It will of course be understood that various changes can be made in the form, details, arrangement and proportions of the parts without departing from the spirit of the invention.

I claim:

l. In a wheeled stretcher, an ambulatory main frame, a stretcher frame above the main frame, a stretcher frame elevator movable to raise and lower the stretcher frame relative to the main frame, an operating screw yother than the one to which the operating screw is connected, a brake element rotatably mounted on the unthreaded portion of the screw shaft for rotation therewith, an overrunning clutch having a relatively stationary portion and a rotatable portion, and said rotatable portion having a braking surface engaging said brake element.

2. The structure in claim 1, and the stretcher frame elevator being connected to the screw follower at an angle to the axis of rotation of the operating screw shaft, whereby a part of the weight moment of said stretcher frame produces axial thrust on the operating screw shaft in the direction of said brake element, the braking surface of said rotatable clutch portion lying in a plane trans versely of the axis of the operating screw shaft and facing toward said screw follower, whereby the axial thrust on the operating screw shaft will maintaink the brake element and braking surface in braking contact.

3. In a wheeled stretcher, an ambulatory main frame, a stretcher frame above the main frame, a stretcher frame elevator having its upper portion connected to the stretcher frame, a rotary elevator actuator connected between the elevator and the main frame including a one-way clutch device locking the elevator against downward movement, a friction brake interposed Vbetween the rotary elevator actuator and the one-way clutch and having cooperating friction surfaces in contact on a plane transverse of the axis of rotation of the rotary actuator, and the elevator being-directionally movable at an angle to the axis of rotation of the rotary actua-tor to impose a weight moment axially of said rotary actuator.

4. In a wheeled stretcher, an ambulatory main frame, a stretcher frame above the main frame, a stretcher frame elevator movable to raise and lower the stretcher frame relative to the main frame, an operating screw shaft rotatably supported by one of said frames and having an unthreaded and a threaded portion, a screw follower on the threaded portion of said screw shaft and connected to said elevator at one part thereof, another part of the elevator being connected to the frame other than the one 4to whichthe operating screw is connected, a brake element rotatably mounted on the unthreaded portion of clutch having a relatively stationary portion anda rotatable portion, said rotatable portion having a braking surface engaging said brake element, said relatively stationary portion having a pair of variably spaced camming elements, a disc rotatably mounted on said operating screw shaft and having an outer portion thereof lying between said camming elements to provide said ovenrunning clutch, and the central portion ,of one face of said disc defining said braking surface.

5. The structure in claim 4, and said relatively stationary portion having opposed inclined ball retainers and said camming elements comprising balls in said ball retainers and engageable with opposite faces of said disc.

References Cited bythe Enea' UNITED STATES PATENTS 836,397 11/1906 McGaugh 5--63 2,521,214 9/1950 Goeller 5-63 2,587,094 2/1952 Berg et al. 5-63 X 2,742,082 4/ 1956 Lief 298--412 2,783,861 3/ 1957 lungles 192-8 2,934,188 4/1960 Bremer 19E-8 FRANK B. SHERRY, Primary .Exdmfwn 

1. IN A WHEELED STRECHER, AN AMBULATORY MAIN FRAME, A STRETCHER FRAME ABOVE THE MAIN FRAME, A STRETCHER FRAME ELEVATOR MOVABLE TO RAISE AND LOWER THE STRETCHER FRAME RELATIVE TO THE MAIN FRAME, AN OPERATING SCREW SHAFT ROTATABLY SUPPORTED BY ONE OF SAID FRAMES AND HAVING AN UNTHREADED PORTION AND A THREADED PORTION, A SCREW FOLLOWER ON THE THREADED PORTION OF SAID SCREW SHAFT AND CONNECTED TO SAID ELEVATOR AT ONE PART THEREOF, ANOTHER PART OF THE ELEVATOR BEING CONNECTED TO THE FRAME OTHER THAN THE ONE TO WHICH THE OPERATING SCREW IS CONNECTED, A BRAKE ELEMENT ROTATABLY MOUNTED ON THE UNTHREADED PORTION OF THE SCREW SHAFT FOR ROTATION THEREWITH, AN OVERRUNNING CLUTCH HAVING A RELATIVELY STATIONARY PORTION AND A ROTATABLE PORTION, AND SAID ROTATABLE PORTION HAVING A BRAKING SURFACE ENGAGING SAID BRAKE ELEMENT. 